In an attempt to increase the horsepower of motorcycles, larger engine blocks are being mounted in conventional motorcycles. One way the mounting for the larger engine block is achieved is by converting the motorcycle to a three wheeled vehicle or by mounting the engine block transverse to the centerline of the motorcycle. Currently, there are no motorcycles which utilize a conventional automobile V-8 engine block.
Several U.S. Patents disclose modified frames to accomplish varied purposes as described hereinafter. U.S. Pat. No. 3,937,484 (Morioka et al.) discloses a motorcycle frame which allows access to the engine mounted below. This access is accomplished by mounting the fuel tank below the seat instead of above the engine.
U.S. Pat. No. 4,047,730 discloses a motorcycle frame for mounting a standard engine. The frame is designed to provide increased flexibility and thus increase rider comfort.
U.S. Pat. No. 4,226,296 (Higaki) discloses a motorcycle frame having a steering head and a pair of upper and lower tubes attached thereto. The lower tubes are designed to suspend a motor which is mounted transverse to the centerline of the frame.
U.S. Pat. No. 4,323,135 (Tominaga et al.) discloses a motorcycle frame for maintaining a standard transversely mounted motorcycle engine.
U.S. Pat. No. 4,660,854 (Suzuki et al.) discloses a motorcycle frame having a main tube connected to the lower end of a steering head so that a gas tank with a larger capacity may be attached to the frame.
U.S. Pat. No. 4,678,054 (Honda et al.) discloses a motorcycle frame which supports a standard motorcycle engine. The frame is provided with a plurality of hollow passages for allowing cable insertion and air flow.
U.S. Pat. No. 4,691,800 (Kadono et al.) discloses a motorcycle frame having a single main frame tube extending from the head pipe to the detachably mounted down frame. The frame is designed to hold a standard motorcycle engine.
U.S. Pat. No. 4,694,929 (Sugimoto) discloses a motorcycle frame having a head pipe and main frame sections having boxed sections which interlock to affix the frame sections to the head pipe.
U.S. Pat. No. 4,735,275 discloses a buggy frame, a four wheeled vehicle, which maintains a transversely mounted engine in the frame.
U.S. Pat. No. 4,852,678 (Yamaguchi) discloses a motorcycle frame having right and left engine support members for maintaining a standard motorcycle engine therebetween. The support members are formed by a plurality of triangular shaped members.
U.S. Pat. No. 5,025,883 (Morinaka et al.) discloses a motorcycle frame having a detachable rear portion. The rear portion of the frame allows for mounting a central trunk as well as left and right trunks.
U.S. Pat. No. 3,508,765 (Bauer et al.) discloses a motorcycle frame having bending moments which are generated in the backbone due to the dynamic loading on the frame. Attached to the backbone are two pairs of tubes which are triangulated with the backbone so that when the backbone is loaded, the tubes act substantially as struts.